Spin alignment of excited projectiles due to target spin-flip interactions

Abstract

The sequential breakup of $E/A=65.5\text{-MeV}\phantom{\rule{4pt}{0ex}}^{7}\mathrm{Be}$ and $E/A=36.6\text{-MeV}\phantom{\rule{4pt}{0ex}}^{6}\mathrm{Li}$ projectiles excited through inelastic interactions with $^{9}\mathrm{Be}$ target nuclei has been studied. For events where the target nucleus remained in its ground state, significant alignment of the excited projectile's spin axis parallel or antiparallel to the beam direction was observed. This unusual spin alignment was found to be largely independent of the projectile's scattering angle and it was deduced that the target nucleus has a significant probability of changing its spin orientation during the interaction. It is proposed that the unusual spin alignment is a consequence of the molecular structure of the $^{9}\mathrm{Be}$ nucleus.